Method and system for displaying via a network of an interactive movie

ABSTRACT

The present invention relates to a system for transferring an interactive walkthrough movie located at a server via a network and displaying the same at a user station, which comprises: (a) a display unit at the user station for displaying movie frames; (b) a control device at the user station for enabling the user to navigate within the movie; (c) a map of the movie describing the links between the individual movie frames and the index of each movie frame, said map also maintains at any given time the present virtual location of the user within the map; and (d) a prediction unit for receiving inputs from said map and from a user control device, and based on said inputs predicting those future frames that may be required for view by the user, and instructing the server to convey said predicted future frames to the user station. The prediction unit may order a first level of resolution frames when the user is in a virtual movement, and a second level of resolution frames when the user is stationary within the interactive movie.

FIELD OF THE INVENTION

The field of the invention relates to systems and methods for displayingmovies via the Internet. More particularly, the invention relates to asystem and method for displaying an interactive movie via a network,such as the Internet, or in a most preferable case, to a system andmethod for displaying via the Internet an interactive movie enabling auser to virtually travel within a physical site, such as a building,office, etc.

BACKGROUND OF THE INVENTION

Virtual movies are widely used for a variety of purposes, such asexhibitions, remote guidance and touring of places, education, training,electronic games, etc. Some of such movies are animated, and some othersare real, in the sense of involving real frames that are photographedwithin a real, physical site and some combine a mixture of real andanimated frames. (It should be noted herein that throughout thisapplication the term “frame” is used to indicate a unitary view that isintroduced to the user at a specific time unit. In this respect, itshould be noted that there is no distinction as to how this frame isproduced, whether by acquiring it fully from the multimedia content, orproducing it from a previous frame by completing only the differencesfrom that previous frame in a manner as some compression tools operate).The present invention relates to all such cases, but mostly to thelatter case; i.e., to the case where the preparation of a virtual andinteractive movie enables a user to interactively explore a real site;i.e., to a case in which a user wishes to watch a movie of a site, andnavigate interactively within the site.

In recent years there have been extensive efforts to streamline theplaying of multimedia over computer networks with no need of a fullmovie preload prior to a continuous playback. Throughout thisapplication, a discussion is made to video movies (or clips), althoughsome aspects of the invention may be relevant to other types ofmultimedia. Most existing solutions take into account the fact that thenetwork bandwidth is limited, and that the speed of transfer dynamicallyvaries. Some solutions suggest the reduction of the amount of datatransferred (e.g., by means of compromising the media quality, or bymeans of compressing the data), and adjustment of the amount of datatransferred to the network speed. The main objective is to obtain asmooth experience with maximum image quality for a given bandwidth. Onecommon solution suggests the performing of a preload of a multimediasequence (such as a movie clip), to balance the stream of theinformation loading during playback, in order to improve theavailability of the clip portions at the user's station, and to preventdelays and suspensions. Throughout this application, the term “station”relates to any type of computer, processor, terminal, workstation, PDA,cellular phone, etc. which has a player for playing a content. Otherfactors that may affect the proper manner of handling multimediainformation at the client side are the size of the data file and theamount of free storage at the user's end. Because the multimedia file atthe remote (server) side is usually large, the fact that it cannotalways be fully stored or fully preloaded to the client side must betaken into account. In such a case, the user's experience may behindered due to the need for a relatively long wait for the data hewishes to play.

The above prior art solutions are relatively satisfactory when playing acontinuous conventional multimedia clip. However, such solutions cannotmeet the stringent requirements of playing an interactive movie via anetwork of limited bandwidth. In a conventional movie the sequence ofthe movie frames is well defined, and therefore the maintaining of aFIFO type register at the user station can assist in the availabilityand integrity of the currently played sequence. However, this is not thecase when playing an interactive virtual movie in which, during manystages of the movie, the user is given several options from which toselect and continue with different sequences of the movie. Thisrequirement to provide several video sequences to the user at any giventime introduces a burden to the effective playing of an interactivevirtual movie via the Internet (or any other bandwidth limited) network.

WO 2004/049263 by same inventors discloses a method and system for thepreparation of an interactive movie, which simulates the walking of auser within a real site and which enables a user to explore the site.Such a virtual movie can be streamed and displayed to a user relativelysmooth, in a high resolution and fast manner. However, any attempt totransfer and simultaneously display this interactive movie via anetwork, such as the Internet, at a station remote from the location inwhich the movie is stored, faces difficulties, particularly insatisfying the interactivity and smoothness requirements.

It is an object of the present invention to provide a method and systemfor the playing of a virtual movie via a bandwidth limited (sometimesvery low bandwidth) network, such as the Internet.

It is another object of the invention to enable playing of such a moviein a manner that minimally affects the quality that the userexperiences.

It is a particular object of the invention to enable the viewing via theInternet (or any other network) of a virtual movie for exploring a site.

Other objects and advantages of the invention will become apparent asthe description proceeds.

SUMMARY OF THE INVENTION

The present invention relates to a system for transferring aninteractive movie located at a server via a network and displaying thesame at a user station, which comprises: (a) a display unit at the userstation for displaying movie frames; (b) a control device at the userstation for enabling the user to navigate within the movie; (c) a map ofthe movie describing the links between the individual movie frames andthe index of each movie frame, said map also maintains at any given timethe present virtual location of the user within the map; and (d) aprediction unit for receiving inputs from said map and from a usercontrol device, and based on said inputs predicting those future framesthat may be required for view by the user, and instructing the server toconvey said predicted future frames to the user station.

Preferably, the system of the invention further comprises a cache unitat the user station for temporarily storing movie frames.

Preferably, the prediction unit orders a first level of resolutionframes when the user is in a virtual movement within the interactivemovie, and a second level of resolution frames when the user isstationary within the virtual movie. Throughout this application theterm “resolution” of a frame is used in its broader interpretation toprovide indication either the number of pixels in a frame or to thequality of the frame, wherein the “quality” indicates the amount of dataor rate of distortion of the frame (for example due tocompression-decompression).

Preferably, the said first level is lower than the said second level.

Preferably, the frames are stored in the server in at least tworesolution levels.

Preferably, the frames are stored in the server in at least oneresolution level, and the server comprises transform means forconverting the frames resolution level to at least one other resolutionlevel.

Preferably, the prediction unit instructs the server to convey a thirdlevel of resolution frames upon a special request by the user.

Preferably, said third level of resolution is the highest resolutionlevel.

In one embodiment, the prediction unit is positioned at the userstation.

In another embodiment, the prediction unit is positioned at the server.

In one embodiment, the map is positioned at the server.

In another embodiment, the map is positioned at the user station.

In still another embodiment, both the prediction unit and the map arepositioned at the server.

In still another embodiment, both the prediction unit and map arepositioned at the user station.

Preferably, the system further comprises a coordinator at the userstation for communicating with said cache and coordinating thedisplaying of frames on the user display.

In an embodiment of the invention, the prediction unit and map arepositioned at the server. Preferably, the system further comprises acoordinator at the user station for communicating with said cache andcoordinating the display of frames on the user display.

In an embodiment of the invention, each frame is conveyed from theserver to the user station associated with one or more of next frameindices, and wherein said coordinator at the user station determinesfrom said next frame indices the order of the frames to be displayed.

Preferably, said coordinator at the user station determines said orderof frames from said one or more next frame indices and from inputs itreceives from said user control device.

Preferably, the system further comprises a transfer coordinator at theserver for coordinating the flow of frames from the server to the userstation.

The present invention further relates to a method for transferring amovie from a remote server via a network and displaying the movie at auser station, which comprises: (a) transferring and displaying to theuser lower resolution frames as long as the user is in movement withinthe movie; and (b) transferring and displaying to the user medium orhigher resolution frames as long as the user is stationary within themovie.

Preferably, the method further comprises the steps of: (a) providing amap of the movie; (b) continuously updating the map with the presentlocation of the user within the movie; and (c) looking at the map and,from the present location of the user, predicting those optional nearfuture frames that may be required for display to the user, and orderingsaid future frames from the server.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows an exemplary scheme of an office, by which a virtual movieis prepared according to the prior art.

FIG. 2 a describes the user side of the system for transferring andplaying a virtual movie according to a first embodiment of theinvention;

FIG. 2 b describes the server side of the system for transferring andplaying a virtual movie according to a first embodiment of theinvention;

FIG. 3 a describes the user side of the system for transferring andplaying a virtual movie according to a second embodiment of theinvention;

FIG. 3 b describes the server side of the system for transferring andplaying a virtual movie according to a second embodiment of theinvention.

FIG. 3 c describes the user side of the system for transferring andplaying a virtual movie according to a variation of the secondembodiment of the invention; and

FIG. 3 d describes the server side of the system for transferring andplaying a virtual movie according to a variation of the secondembodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A virtual movie is a movie which enables a user to view video (orsequences of frames), in which the user has, in at least some placeswithin the movie, the option of selecting which video segment will bedisplayed to him. Therefore, in contrast to the case of a regular moviein which the whole sequence and order of the movie is fixed, predefinedand known, in a virtual movie the order of the movie segments is left tothe user's discretion. Therefore, the transfer of the movie over anetwork for playing in a user's station (which requires real timeavailability of the movie frames at the user station) becomes much morecomplicated, especially when the bandwidth of the network is relativelylow. Of course, the higher the resolution of the movie and the largerthe content of the whole movie are, the more complicated this real timeavailability problem of the movie frames at the user station becomes.

As previously said, at any given time at least a portion (generally madefrom a sequence of frames) of the future movie segments that the userwishes to view has to be available at his station. However, in view ofthe interactivity, and as there are points in the movie in which theuser has several movie segments to select from, at least a portion ofeach of said optional segments has to be available for display at hisstation at the time the selection is made, in order to assure smooth andcontinuous viewing. This interactivity requirement further increases thechallenge that the present invention faces.

In any virtual movie, there are times in which the user navigates whilebeing in movement, and there are other times in which he stops, andfocuses in a specific view. One aspect of the present invention is theobservation that during the “movement” of the user, in which the movieframes are rapidly changed, the resolution can be reduced, as it isassumed that during movement the user does not have a high interest inany specific view included in the rapidly changed sequence of frames.Moreover, during said “movement” periods, the rate of change of theframes enables such reduction of resolution not to severely disturb theuser experience. However, when the user “stops” and focuses on aspecific view, it is assumed that he has a high interest in said view,and therefore in such “stopping” times a frame with an increasedresolution is provided to the user and displayed to him. Furthermore,according to a preferred aspect of the invention, in all such userstopping points the user is given the option of requesting andimmediately receiving a highest resolution frame.

Every movie comprises one or more sequences of frames. A conventionalmovie is essentially one long sequence of frames, while a virtual movieis comprised of several segments, each segment comprising a sequence offrames. The virtual movie also includes at least several junctionlocations in which a user can select from two or more optional segmentsto continue. The rate of virtuality of the movie is generally limited,as the user cannot go from each point to all other points in the movie,but he can do so only from some junctions. Therefore, the sequence offrames within a segment is generally fixed, but the transfer from onesegment to another is flexible.

The present invention assumes the availability of a digital scheme (alsoreferred to herein as “map”) of the movie, indicating all possibleroutes of the movie, including all those junctions and optional segmentsgiven to the user in each junction. Such a scheme contains at leastseveral segments of frames. In each segment, each movie frame isconnected to at least one, and generally to more than one next and/orprevious frames of the segment. A connection of a frame to a previousframe may be referred to as an “entry” and each connection of a frame toa next frame may be referred to as “exit”. An example of such a schemeand a virtual movie is provided in WO 2004/049263.

FIG. 1 shows an exemplary scheme of an office, by which a virtual movieis prepared according to WO 2004/049263, the full content of which isincorporated herein by reference. It should be noted that the thisscheme is provided herein as an example only, as the present inventionmay operate with various types of schemes, as long they contain at leastthe linkages between frames, junctions, and several optional segments asdescribed above.

The scheme of FIG. 1 shows an office 10 having two corridors (C1, C2)and two rooms (A, B). WO 2004/049263 shows how to produce a virtualmovie enabling a user to navigate; i.e., to “walk” around the office. Asseen, while beginning at point 11, the user walks up to junction J1, atwhich he may either turn right into room B or continue straight ahead.Similarly, when arriving at junction J2, the user may either turn rightinto room A or go straight ahead along corridor C1. When arriving atjunction J3, the user may either turn to the right or to the left withincorridor C2. Furthermore, while walking along the corridor, the usergenerally needs to have a relatively limited field of view. In junctionsJ1, J2, and J3 the user needs a wider field of view, and in rooms A andB he generally needs a field of view of 360°. For example, in junctionJ1 the user may select the option of continuing along the corridor andview up to the end of the corridor, or he may select the option ofturning into room B and see the view of room B, or he may decide to turnback and return along the corridor C1.

WO 2004/049263 describes one way of producing a virtual movie which canbe described in a form of a scheme, which is suitable for carrying outthe invention. An office is filmed by means of a scanning apparatuswhich captures frames in up to a 360° field of view. The scanningapparatus is moved forward along the route, while capturing photographsin a relevant (predefined) field of view, from a plurality of filmingspots (nodes).

The plurality of points along the route in which the scanning (filming)is performed is indicated in FIG. 1 as nodes 13. The nodes 13schematically indicate in each specific node location the manner ofscanning at that point, and provide other parameters that are specificto this node.

It should be noted that the interactivity of the movie enables the userin some, generally junction, locations to decide between two optionalcourses. For example, assume that the user “walks” from node point 15toward junction J1. When he arrives at junction J1, he can eithercontinue in the corridor C1, or turn right to room B. Therefore, priorto the user arriving at junction J1 (for example, at point 17), thedisplay at the user station should already include both the frames ofroom B (node 20, 27, . . . ) and the frames of the continuing portion ofthe corridor C1 (nodes 21, 28, . . . ).

Before the filming stage according to WO 2004/049263, a plan is maderegarding the routes along which the filming will be made. Along theplaned routes, the nodes are created when the scanning apparatus passesa predefined distance D, which may be, for example, every 5-50 cm, orchanges its angular orientation by a predefined angle Δ° (for example5). For each node, a specific camera unit field of view is created. Theterm “camera unit field of view” defines the angular for each node, acumulative field of views that are captured by the individual cameraforming the camera unit. Then, the scanning apparatus progresses alongthe planned routes and captures frames.

WO 2004/049263 therefore assumes that the interactive virtual movie is acollection of image data frames that are captured along routes withinthe physical site. This is translated to a linked scheme of nodes suchas of FIG. 1 in which every node comprises an image data that representsa camera unit field of view. The connection from one node to another(i.e., from a selected user field of view (UFOV) in a first node toanother (UFOV) in another node) is maintained smooth. The links betweennodes allow movement from one node to another in a smooth manner. At theend of the filming process, the movie is essentially ready for use.Thereafter, when the movie is activated, the user may “move” from afirst node, viewing a selected view sector, to a second node viewinganother view sector, however in closeness enough to maintain smoothnessof view. The “moving” of the user from one frame to a next frame isperformed by directing the center of the user field of view to an exitdirection of the present node, and advancing to the node linked to saidpresent node by said exit. The entry of the user to said next node ismade by showing to the user the user field of view (portion of the nextnode image data) when the center of the user field of view points to theentry direction of said next node.

It should be noted that each segment of the movie has preferably itsunique reference number, and all the frames within each segment alsoreceive reference numbers, preferably according to their sequentialorder within the segment.

As said, the invention of WO 2004/049263 enables a user to virtuallynavigate in the filmed site, by moving in various directions, and bylooking at selected directions. The user is provided with a player, andthe movement is made by means of a pointing device, by the arrow of thekeyboard, by a joystick, etc. The movie contains a very large amount ofdata, which does not enable a smooth view by a user via a narrowbandwidth network, such as the Internet. The fact that the movie isinteractive, which provides to the user the option of deciding in whichdirection to look, and furthermore, in junctions such as junction J1 inwhich direction to move, multiplies by several orders the amount of datathat has to be handled in real time. When trying to enable a user toview such a movie via the Internet, this problem becomes much morecomplicated.

FIGS. 2 a and 2 b illustrate in schematic general form a system for thetransfer via the Internet (or any other network) and play at the userend of a virtual movie. FIG. 2 a illustrates the structure of the system100 at the user end, and FIG. 2 b illustrates the structure of thesystem 150 at the server end. With reference to FIG. 2 a, the displayunit 101 receives frames via channel 102 and displays them on the user'sscreen. The display unit displays either video (which is essentiallystills frames that are displayed at a high rate) or stills frames. Itshould be mentioned, that the data via channel 102 may only includeupdates to a previous frame already displayed, in a manner known in theart. The exploration coordinator 103, among other tasks which willbecome apparent hereinafter, coordinates the transfer of the frames viachannels 104 and 102 from cache unit 105 to the display unit 101. Theexploration coordinator 103 orders and verifies the availability of theordered frames in cache unit 105 by means of line 106. The cache unit105 is a storage for the frames that are received from the server 150(FIG. 2 b). Due to its limited storage space, it is expected that notall the movie frames will be stored in the cache, and therefore thecache stores only the frames that have been received and are necessaryfor the display of the movie (i.e., those frames that are most expectedto be used). Those frames which have already been displayed (ordetermined to be unnecessary) may be cleared from the cache and replacedby newly arrived frames. The control device 107 is the device which theuser uses for navigation in the movie. As is typical in the art, thismay be the mouse of the user, a joystick, the keyboard, etc. The userintention to move to a specific direction (for example to go straightahead using the corresponding keyboard arrow) is reported over lines 111a and 111 b respectively from the control device 107 to both theprediction & frame ordering coordinator (hereinafter “PFOC”) 108, and tothe exploration coordinator 103. The exploration coordinator 103, whichalso receives the present location of the user from map 109 over line122, determines from the said user intention and from his presentlocation on the map the new frame which has to be shown to the user. Inthis respect, it should be noted that map 109 is digital scheme of themovie, on which the present location of the user in the movie isindicated, and is continuously updated (line 139) according to the usermovement. The exploration coordinator 103 checks the availability of thenew frame in cache 105. If the said new frame is available, and as willbe apparent by the following description, it is most probably available(due to the operation of the PFOC 108); the frame is immediately fetchedfrom the cache, sent to the display unit over channel 102 and displayedto the user. If not, the exploration coordinator 103 waits until thisframe becomes available in the cache 105, and only then it fetches theframe and sends it to the display unit 101 over channel 102. Any timewhen a new frame is sent to the display unit 101, the explorationcoordinator updates (line 139) the location of the user on map 109.

The PFOC 108 continuously receives updates 122 relating to the locationof the user on the map 109, predicts the next movements of the user, andaccordingly orders the necessary frames from the server 150 (it onlyorders those frames that are not already in the cache), in order toassure their availability at the display unit for maintaining smoothmovie playing. It should be noted that, within continuous segments wherethe user's next movement is clearly defined, all or some of the framesup to the next junction may be ordered; but if there is an approachingjunction, the PFOC 108 orders frames relating the routes that follow thejunction. The number of frames that are ordered from said routes mayvary. If at some stage one of the said several optional routes becomesevident, the frames corresponding to this route are displayed to theuser. The frames that have not been used for the longest time may bedeleted from the cache and replaced by newly coming frames. The PFOC 108may operate in such a manner as to optimize the availability of framesat the cache when they are needed. If it is found that ordering a fewfuture frames in each order is enough to ensure smoothness, this ispreferable, as in this manner it is expected that fewer frames will beordered and not finally used. In said latter case, more orders operationfrom the server 150 will be performed. The ordering by the PFOC 108generally involves two steps: in the first step the PFOC checks theavailability (line 112) of the necessary frames at the cache unit 105,and the second step involves the ordering (line 113) from the server ofonly the frames that are not available in the cache unit 105. The cache,in turn, reports the availability of frames over line 114 to both thePFOC 108 and to the exploration coordinator 103. The ordered frames fromthe server are conveyed to the user end 100 over channel 116. As said,the exploration coordinator 103 also receives updates 122 relating tothe present location of the user on the map 109, as it needs thisinformation in order to determine at any given moment what the nextvirtual location of the user in the map will be and the exact frame thathas to be fetched from the cache and conveyed to the display unit 101.

Preferably, the operation of the PFOC is enhanced to also continuouslycheck the streaming of the frames from the server to the user station,in order to eliminate the transfer of frames from the server that arefound to be no longer necessary at the user station. For example, theremay be cases in which a sequence of future frames has been ordered fromthe server, but while a portion of said sequence has not been yettransferred it is determined that this portion is no longer required atthe user station (such a case may be, for example, due to a predictionby the PFOC that subsequently been found to be non-relevant) the PFOC108 issues a signal to the server to cancel the transfer of those framesthat are found to be no longer necessary.

The system as described, and particularly the use of a prediction unitand map, ensures that the future frames are available at the displayunit 101 whenever they are required to ensure smooth play. The use ofcache further enhances the system by ensuring that frames that areavailable at the user end (in cache unit 105) are not reordered, butthey are fetched from the cache.

As previously said, still another aspect of the invention involves theuse of two or more resolution levels of the frames that are ordered anddisplayed to the user. FIG. 2 b describes the structure of the serverend 150 in a block diagram form. The movie is preferably stored at theserver in three storages relating each to a different level ofresolution, a low resolution storage 151, a medium resolution storage152, and a high resolution storage 153.

According to a preferred embodiment of the invention, still anotherobject of the PFOC 108 is to determine the movement type of the user. Assaid, the PFOC 108 receives indications relating to the user movementfrom the control device 107 over line 111 a. Therefore, and for thereasons explained above, when the PFOC 108 determines that the user isin movement, it orders from the server low resolution frames. Wheneverthe PFOC 108 determines that the user stops and looks intently to aspecific view, the PFOC 108 orders a medium resolution frame. However,when the user wishes to closely examine a specific view, he is providedwith means, such as a button in the user interface, for ordering such ahigh resolution frame. This indication is conveyed over line 120 to PFOC108, which in turn orders the highest resolution frame from the server.It should be noted that whenever a medium resolution frame or a highestresolution frame is ordered, the whole frames transfer is halted (orreduced to low priority); and the channel 116 is solely (or mostly)dedicated to the transfer of said medium or highest resolution frame. Itshould be noted, however, that this transfer halt of the low resolutionframes is very short, as only one frame is transferred. When saidordered medium resolution or high resolution frame arrives in the cache,the regular process of low resolution frames transfer resumes.

The exploration coordinator 103 uses the movement information 111 b inorder to determine at any moment the frame required by the client. Itfurther checks the availability of this frame in cache 105, and assumingit has already been ordered by the PFOC 108 and exists in cache 105, theexploration coordinator fetches the frame, and conveys this frame overchannel 102 to the display unit 101.

With reference to FIG. 2 b, the transfer coordinator 157 receives theorders for frames and the desired resolution for each order over line113. It sends a fetch signal over a respective one line 170, 180, or190, and receives the fetched frames over a respective channel 171, 181,or 191. The transfer coordinator 157 then coordinates the transfer ofthe frames that are conveyed via channel 116, and the network to theuser end 100.

It should be noted that the three storages for the three levels ofresolution have been given herein as an example only. Instead of threeseparate storages, there may exist only one, high resolution storage,and whenever other resolution level is ordered, the high resolution maybe transformed by the transfer coordinator 157 into the desiredresolution before the transfer.

As shown, in the first embodiment, the map must be located at the userend. Therefore, in the first embodiment, when a user wishes to view aspecific interactive movie, the map of that movie is first transferredto the user side.

FIGS. 3 a and 3 b illustrate in schematic general form a secondembodiment of the invention. The operation of the second embodiment issimilar to the operation of said first embodiment. However, while in thefirst embodiment most of the units that are responsible for theprocessing are located at the user side, in the second embodiment mostof the said processing units are located at the server side.

FIG. 3 a illustrates the structure of the system 200 at the user end,and FIG. 3 b illustrates the structure of the system 250 at the serverend. With reference to FIG. 3 a, the display unit 201 receives framesvia channel 202 and displays them on the user's screen. The display unitdisplays either video (which is essentially stills frames that aredisplayed at a high rate) or stills frames. It should be mentioned thatthe data via channel 202 may only include updates to a previous framealready displayed, in a manner known in the art. The display coordinator218 coordinates the transfer of the frames via channels 204 and 202 fromcache unit 205 to the display unit 201. The display coordinator 218receives on line 229 the indication of the frame that has to becurrently displayed, information regarding the current position and therelevant future or current options accordingly. It verifies theavailability of this current frame in cache unit 205 by means of line206. The cache unit 205 acts as storage for the frames that are receivedfrom the server 250 (FIG. 3 b). Due to its limited storage space, it isexpected that not all the movie frames will be stored in the cache. Thecache stores only the frames that have been received and are necessaryfor the display of the movie (i.e., those frames that are most expectedto be used). Those frames which have already been displayed (ordetermined to be unnecessary) may be cleared from the cache and replacedby newly arrived frames. The control device 207 is the device which theuser uses for navigation in the movie. As is typical in the art, thismay be the mouse of the user, a joystick, the keyboard, etc. The user'sintention to move to a specific direction (for example to go straightahead using the corresponding keyboard arrow) is reported from thecontrol device 207 over line 211 to server 250. In server 250 (FIG. 3b), the user's intention is reported to both the PFOC 208 (line 211 a)and to the exploration coordinator 203 (line 211 b). The explorationcoordinator 203 which also receives the present location of the userfrom map 209 over line 222 determines, from the said user's intentionand from his present location on the map, the new frame which has to beshown to the user. The indication for the new frame (actually thepresent frame) is conveyed over line 229 to the user side 200 (FIG. 3a). As in the previous embodiment, map 209 is a digital scheme of themovie, on which the present location of the user in the movie isindicated, and is continuously updated (line 239) according to the usermovement. At the user end, the indication 229 for the new frame isprovided to the display coordinator 218. The display coordinator 218checks (line 206) for the availability of the new frame in cache 205. Ifthe said new frame is available, and as will be apparent by thefollowing description, it is most probably available (due to theoperation of the PFOC 208), the frame is immediately fetched from thecache, sent to the display unit 201 over channel 202, and displayed tothe user. If not, the display coordinator 218 waits until this new framebecomes available in cache 205, and only then it fetches the frame andsends it to the display unit 201 over channel 202.

The PFOC 208 continuously receives updates 222 relating to the locationof the user on the map 209, predicts the next movements of the user andaccordingly orders the necessary frames from one of the three framesstorages (low resolution storage 251, medium resolution storage 252, orhigh resolution storage 253). As will be described hereinafter, in mostcases the order will be performed from the low resolution storage 251.This is done in order to assure the availability of the necessary framesat the display unit for maintaining smooth movie playing. It should benoted that, within continuous segments where the user next movement isclearly defined, all or some of the frames up to the next junction maybe ordered. However, if there is an approaching junction, the PFOC 208orders frames relating to the routes that follow the junction. Thenumber of frames that are ordered from said routes may vary. The PFOC108 may operate in such a manner as to optimize the availability offrames at the cache 205 (at the user side) when they are needed. Thecache 205 at the user side may generally operate in such a manner thatthose frames that have been longest in non-use are replaced by new ones.The ordered frames from the relevant storage are conveyed to thetransfer coordinator 257, which in turn transfers them over channel 216of the network to the user side for display.

As previously said with respect to the embodiment of FIGS. 2 a and 2 b,there may be cases in which a sequence of future frames has beenassigned for transfer from the server to the user station, but while aportion of said sequence has not been yet transferred it is determinedthat this portion is no longer required at the user station (such a casemay be, for example, due to a prediction by the PFOC that subsequentlybeen found to be non-relevant). In similarity to the embodiment of FIGS.2 a and 2 b, also in this case the PFOC 208 cancels the transfer ofthose frames that are found to be no longer necessary at the userstation.

The system as described, and particularly the use of a predictioncoordinator and map 209, ensures that the future frames are available atthe display unit 201 whenever they are required to ensure smooth play.The use of cache further enhances the system by ensuring that framesthat are available at the user end (in cache unit 205) are not reorderedbut are fetched from the cache.

As in the first embodiment, the operation of the second embodiment alsoinvolves the use of several resolution levels of the frames that aredisplayed to the user. As long as the PFOC 208 determines from thesignal over line 211 a (the movement controls from the control device207) that the user is in movement, the PFOC 208 orders and causes lowerresolution frames (from storage 251) to be sent to the user. Wheneverthe prediction coordinator 208 determines that the user stops moving, itimmediately orders the transfer coordinator to halt the transfer. Itthen orders a medium resolution frame from storage 252 and sends thismedium resolution frame to the user end. If, on the other hand, the PFOC208 determines that the user wishes to view a high resolution frame, theorder is made and conveyed in a similar manner from the high resolutionstorage 253.

In the embodiment of FIGS. 3 a and 3 b the cache unit 205 is located atthe user station, while the PFOC 208 is located at the server. The PFOC208, when deciding whether to convey specific frames to the user or not,has to check the content of the cache unit 205, and to send frames onlyif they are missing from the cache 205. In one embodiment, the PFOC 208periodically checks and receives updates regarding the availability ofspecific frames in the cache 205, in order to be able to determinewhether specific frames should be sent or not. In another example theserver also contains a user cache image 264, which stores currentinformation regarding the content (the frames indexes but not the framesthemselves) of cache 205. The user cache image 264 is updated when thecontent of cache 205 changes, in order to reflect the true and currentcontent of cache 205. In one option, the updates are provided from theuser station as shown by line 267. In another example, the servermaintains an algorithm 269, which operates exactly according to similaralgorithm at the user station which governs the content of cache 205(i.e., which frames in the cache to delete in order to vacant a spacefor new frames). In such a manner, and using said algorithm 269, theUser Cache Image 264 can always be updated according to the content ofcache 205, as same algorithm is performed and govern the content at saidtwo locations.

FIGS. 3 c and 3 d illustrate in block diagram form still anotherembodiment of the invention. This embodiment is essentially similar tothe embodiment of FIGS. 3 a and 3 b, with some modifications as follows.In the embodiment of FIGS. 3 a and 3 b a signal “frame to display 229”is sent from the server to the user station, and this signal determinesat any given time which frame is displayed at the user's display.According to the embodiment of FIGS. 3 c and 3 d this signal iseliminated. Instead, each frame which is sent from the server to theuser station over channel 216 is associated with the index of the nextneighboring frame (or several indices when the frame is followed byseveral optional frames). By the term “next”, it is meant herein anypossible adjacent frame to the current one, i.e., for example, a framebefore, after, to the side, etc. The said associated indices of theframes are also saved, enabling the system to determine at any giventime when a frame is displayed the next frame to display. In most cases,this task is simple, as in most cases there are only a few possible nextframes, and therefore only a few next frame indices are associated withthe frame. However, for example in a junction frame, there may beseveral optional indices that are associated with the frame, and thedisplay coordinator 218 has to determine which of the next optionalframes it has to display. This decision can be made by means ofproviding to the display coordinator 218 a direction input 277 fromcontrol device 207. Using this indication, the coordinator 218 canselect the right frame to display.

In another aspect of the invention, it has been found thatsimultaneously with the playing of the movie, it is preferable todisplay to the user a small version of the site map, on which thepresent user location is displayed. Therefore, according to a preferredembodiment before playing the movie the site map is initiallytransferred from the server to the user. Thereafter, each time a frameis transferred from the server to the user station, the x;y locationfrom where the frame was captured and also the view direction are alsotransferred associated with the frame. This additional data is alsostored in the cache at the user station. When the virtual movie isplayed at the user station, said additional small map is also displayed,and using said additional data, the current user location and his viewdirection are also displayed over the map.

It should also be noted that the three storages for the three levels ofresolution have been given herein as an example only. Instead of threeseparate storages, there may exist only one, high resolution storage,and whenever other resolution level is ordered, the high resolution maybe transformed by the transfer coordinator 157 into the desiredresolution before the transfer. Furthermore, while in the firstembodiment the map has to be transferred to the user side, according tothe second embodiment this transfer of the map to the user side is notrequired. It should further be noted that the present invention does notpreclude preloading of a portion of the movie prior to playing of theinteractive movie. As in the prior art, the use of preload may beadvantageous, particularly in slow networks.

While some embodiments of the invention have been described by way ofillustration, it will be apparent that the invention can be put intopractice with many modifications, variations and adaptations, and withthe use of numerous equivalents or alternative solutions that are withinthe scope of persons skilled in the art, without departing from thespirit of the invention or exceeding the scope of the claims.

1. System for transferring an interactive movie located at a server viaa network and displaying the same at a user station, which comprises: a.a display unit at the user station for displaying movie frames; b. acontrol device at the user station for enabling the user to navigatewithin the movie; c. a map of the movie describing all the links betweenthe individual movie frames, and the index of each movie frame, said mapalso maintaining at any given time the present virtual location of theuser within the map; and d. a prediction unit for receiving inputs fromsaid map and from a user control device, and based on said inputspredicting those future frames that may be required for view by theuser, and instructing the server to convey said predicted future framesto the user station.
 2. System according to claim 1, further comprisinga cache unit at the user station for temporarily storing movie frames.3. System according to claim 1, wherein the prediction unit orders afirst level of resolution frames when the user is in a virtual movement,and a second level of resolution frames when the user is stationarywithin the virtual movie.
 4. System according to claim 3, wherein thesaid first level is lower than the said second level.
 5. Systemaccording to claim 3 wherein the frames are stored in the server in atleast two resolution levels.
 6. System according to claim 3 wherein theframes are stored in the server in at least one resolution level, andthe server comprises transforming means for converting the framesresolution level to at least one other resolution level.
 7. Systemaccording to claim 1, wherein the prediction unit instructs the serverto convey a specific level of resolution frames upon a special requestby the user.
 8. System according to claim 7 wherein said specific levelof resolution is the highest resolution level.
 9. System according toclaim 1 wherein the prediction unit is positioned at the user station.10. System according to claim 1 wherein the prediction unit ispositioned at the server.
 11. System according to claim 1 wherein themap is positioned at the server.
 12. System according to claim 1 whereinthe map is positioned at the user station.
 13. System according to claim2, wherein the prediction unit and the map are positioned at the userstation.
 14. System according to claim 13, further comprising acoordinator at the user station for communicating with said cache andcoordinating the display of frames on the user display.
 15. Systemaccording to claim 2 wherein the prediction unit and map are positionedat the server.
 16. System according to claim 15, further comprising acoordinator at the user station for communicating with said cache andcoordinating the display of frames on the user display.
 17. Systemaccording to claim 15, wherein each frame is conveyed from the server tothe user station associated with one or more of next frame indices, andwherein said coordinator at the user station determines from said nextframe indices the order of the frames to be displayed.
 18. Systemaccording to claim 17, wherein said coordinator at the user stationdetermines said order of frames from said one or more next frame indicesand from inputs it receives from said user control device.
 19. Systemaccording to claim 1, further comprising a transfer coordinator at theserver for coordinating the flow of frames from the server to the userstation.
 20. Method for transferring a movie from a remote server via anetwork and displaying the movie at a user station, comprising: a.transferring and displaying to the user lower resolution frames as longas the user is in movement within the movie; and b. transferring anddisplaying to the user medium or higher resolution frames as long as theuser is stationary within the movie.
 21. Method according to claim 20,further comprising the steps of: c. providing a map of the movie; d.continuously updating the map by the present location of the user withinthe movie; e. looking at the map, from the present location of the userpredicting those optional near future frames that may be required fordisplay to the user, and ordering said future frames from the server.